Synthetic elastomeric isocyanate modified polymers and method for their preparation



United States Patent ()fiice 2,801,990 Patented Aug. 6, 1957 2,801,990SYNTHETIC ELASTOMERIC ISOCYANATE MODI- FIED POLYMERS AND METHDD FORTHEIR PREPARATION No Drawing. Application November 12, 1952, Serial No.320,128

6 Claims. (Cl. 260-45) This invention relates to organic chemicalcompositions and to methods for their preparation. More particularly itrelates to polymeric compounds and to their preparation. Still moreparticularly, it relates to synthetic elastomeric materials and tomethods for their preparation. The particular class of organiccompositions to which this invention relates are those resulting fromthe reaction of a polyisocyanate and an elastomericdiisocyanate-modified polyester or polyesteramide, containing aplurality of certain functional groups possessing reactive hydrogen.

The reactivity of the isocyanate radical with compounds containingreactive hydrogen is known. In certain chemical reactions wherepolyisocyanates are employed, the marked reactivity of the isocyanateradical results in certain difficulties. For example, trouble isencountered when the rate of reaction between the isocyanate radicalsand the groups containing reactive hydrogen is so rapid that the finalreaction product is formed before a useful article of commerce can befabricated from that product. This is particularly true where apolyisocyanate is used to cure or cross-link diisocyanate-modifiedpolyesters or polyesteramides such as those described in our co-pendingapplications Serial Numbers 187,696,

filed September 29, 1950, now United States Patent 2,625,532; 305,914,filed August 22, 1952, now United States Patent 2,680,308; 307,900,filed September 4, 1952, now Patent 2,702,107; and 312,161, filedSeptember 29, 1952, now United States Patent 2,625,535. If theisocyanate radicals react too rapidly, a cure of the uncured material iseffected before the material can be processed through the manufacturingsteps required to fabricate a useful article.

It is therefore an object of this invention to provide an improvedmethod for the preparation of elastomeric polymeric materials formedfrom the reaction of polyisocyanates. Another object is to prepare suchelastomen'c polymeric materials using a method whereby thepolyfunctional reactivity of the polyisocyanate can be controlled. Aspecific object is to provide new polymeric compounds of a rubber-likenature in which the rate of cure or cross-linking of the new compoundscan be controlled. Other objects will become apparent as the descriptionproceeds.

In its simplest form, the preparation of the polymeric materials from apolyisocyanate and the other reactant containing a plurality of groupshaving reactive hydrogen may be represented by the following equation:

where R and R are organic radicals. It is evident that both reactantsmust be bifunctional if linear polymeric materials are to be formed. Ifeither or both reactants have more than two functional groups, a polymerresults which is interlinked, i. e., both linearly-linked and 2cross-linked, and it is primarily this inter-linking reaction with whichthe present invention is concerned.

According to the practice of this invention, a method is providedwhereby the reactivity of a plurality of -NCO groups may be controlledby the temperature ot the reacting mixture. This method comprises firstforming an adduct of the polyisocyanate by inactivating atleast one butnot all of the -NCO groups in the polyisocyanate by reaction withcertain compounds containing reactive hydrogen. These adducts, onceformed, will dissociate into their original components when subjected tothe action of heat, with the result that the complete polyfunctionalcharacter of the polyisocyanate is restored. The formation of themono-adducts, as some of these compounds can be called, may berepresented by the following equation:

OCNR-NCO +H-R (T). OONRl IO R in which R and R" are organic radicals.

It will be noted that the reaction between the polyisocyanate and theadduct-forming compound is a reversible one, the direction of which maybe controlled by temperature and/or a catalyst. The mono-adduct isformed at relatively low temperatures while the formed adductdissociates into the polyisocyanate and the adduct-forming compound atrelatively high temperatures, for instance, in the range of from C. toC. In some instances a temperature as high as. 200 C. or higher isnecessary to effect the dissociation of the formed mono-adduct. It isthis temperature control over the direction of the reaction which makesthe adducts particularly useful as a means of controlling the rate ofreaction between the adducts and the compound containing reactivehydrogen. When some of the isocyanate groups are blocked from reactingwith the available hydrogen in the polymer-forming material, it isevident that the linear formation and cross-linking of the reactants ismaterially reduced. Upon the application of heat to the system, theblocked isocyanate groups are released, as represented by the reversiblereaction shown in Equation 2, and may then react with the reactivehydrogen present in the polymer-forming material to form crosslinkedpolymers. The mono-adducts are also useful as a means for controllingthe tendency of polyisocyanates to self-polymerize since theinactivation of one active -NCO group will retard such polymerization.

The overall reaction may be most simp1y represented by the followingequation:

Although the reactions shown have been represented, for the sake ofsimplicity, as applied to a diisocyanate, a bifunctional reactant, and amono-adduct of a diisocyanate, it is to be understood that thisinvention relates to polyisocyanates, polyfunctional reactantscontaining a plurality of reactive hydrogens, and poly-adducts ofpolyisocyanates as well. For instance, this invention embraces the useof a mono-adduct or a di-adduct of a triisocyanate, a mono-adduct,di-adduct, or tri-adduct of a tetraisocyanate, and similar adducts ofother polyisocyanates. The invention is generically applicable to theuse of polyisocyanate adducts in which at least one but not all of theisocyanate groups have been temporarily inactivated by reaction with anadduct-forming compound. The number of isocyanategroups which areblocked or inactivated by reaction with the adductforming compound maybe controlled by the molccula r acetone, benzimidazole,

3 proportions of polyisocyanate and adduct-forming compound used to formthe adducts.

In the formation of the adducts, and subsequently the formation of thepolymeric materials, as by reaction between the adduct andpolymer-forming materials, any polyisocyanate may be used.Representative examples are the aliphatic compounds such as' ethylene,trirnethylene, tetramethylene, pentamethylene, hexarnethylene,propylene-1,2; butylene-1,2; butylene-2,3; butylene-l,3; ethylidene andbutylidene diisocyanates; the cycloalkylene compounds such ascyclopentylene-l,3; cyclohexylene- 1,4; and cyclohexylene-1,2diisocyanates; the aromatic compounds such as m-phenylene, p-phenylene,4,4'-diphenyl, 1,5-naphthalene, and 1,4-naphthalene diisocyanate's; thealiphatic-aromatic compounds such as 4,4- diphenylene methane, 4,4'-tolidine, 1,4-xylylene and the tolylen'e' diisocyanates such as2,4-toly1ene diisocyanate; the nuclear substituted aromatic compoundssuch as dianisidine diisocyanate, 4,4-diphenyl ether diisocyanate andchloro-diphenylene diisocyanate; the triisocyanates such as4,4',4-triisocyanto triphenyl methane; 1,3,5- triisocyanto benzene; and2,4,6-triisocyanto toluene; and the tetraisocyanates such as4,4'-dimethyl-diphenyl methane 2,2',5,5-tetraisocyanate.

The polyisocyariates which are particularly preferred in the preparationof the mono-adducts are 4,4'-diphenyl diisocyanate, 1,5-naphthalenediisocyanate, the meta tolylene diisocyanates such as 2,4-tolylenediizocyanate and 4,4-diphenylene methane diisocyanate.

The adduct-forming compounds which are used to react with thepolyisocyanate cannot be any compound containing hydrogen reactable withthe -NCO group. Certain adducts formed are so stable that reversing thereaction by heat alone is not possible. It has been found that theadduct-forming compounds should be selected from the group comprising:

1. Tertiary alcohols such as tertiary butyl alcohol, tertiary amylalcohol. dimethyl ethinyl carbinol, dimethyl phenyl carbinol, methyldiphenyl carbinol, triphenyl carbinol, l-nitro tertiary butyl carbinol,l-chloro tertiary butyl carbinol, and triphenyl silinol;

2. Secondary aromatic amines which contain only one group having ahydrogen reactive with an isocyanate group, suchas the diaryl compoundswhich are preferred, including diphenyl amine, o-ditolyl amine,rn-ditolyl amine, p-ditolyl amine, N-phenyl toluidine, N-phenylxylidine, phenyl alpha naphthyl amine, phenyl beta naphthyl amine,carbazole, andthe nuclear substituted aromatic compounds such as2,2-dinitro diphenyl amine and 2 2 -dichloro diphenyl amine;

3. Mercaptans such as 2-mercaptobenzothiazole, 2-mercapto thiazoline,dodecyl mercaptan, ethyl Z-mercapto thiazole, dimethyl Z-mercaptothiazole, beta naphthyl mercaptan, alpha naphthyl mercaptan, phenyl2-mercapto thiazole, Z-mercapto 5chloro-benzothiazole, methyl mercaptan,ethyl mercaptan, propyl mercaptan, butyl mercaptan, and ethinyl dimethylthiocarbinol;

4. Lactams such as epsilon-caprolactam, delta-valerolactam,gamma-butyrolactam, and beta-propiolactar'n;

5. Imides such as carbimide, succinimide, phthalimide, naphthalimide,and glutarimide;

6. Monohydric phenols in which the hydroxyl group is the only groupcontaining hydrogen reactive with the isocyanate group, such as phenol,the cresols, the xylenols, the trime'thyl phenols, the ethyl phenols,the propyl phenols, the chloro phenols, the nitro phenols, the thymols,

the carva'crols, mono alpha phenyl ethyl phenol, di alpha phenyl ethylphenol, tri alpha phenyl ethyl phenol, and tertiary butyl phenol;

7. Compounds containing enolizable hydrogen such as aceto-aeetic ester,diethyl malonate, ethyl n-butyl malonate, ethyl benzyl malonate, acetylacetone, acetonyl and 1-phenyl-3 methyl 5- pyrazolon.

The adduct-forming compounds should, of course, possess only one groupcontaining a reactive hydrogen atom. The presence of more than one suchgroup would permit polymerization reactions with the polyisocyanate,which are not desired.

The preferred adduct-forming compounds are diphenyl amine, phenyl betanaphthylamine, succinimide, phthalimide, tertiary butyl alcohol,tertiary amyl alcohol, dimethyl ethinyl carbinol, acetoacetic ester,diethyl malonate, mono alpha-phenyl ethyl phenol, epsilon-caprolactam,and Z-mercaptobenzothiazole.

The adducts formed by reacting a polyisocyanate with a compound from thegroups listed above will, it has been found, dissociate into theoriginal components upon application of heat to the system, so that suchadducts may be mixed with reactants having a plurality of groupscontaining reactive hydrogen with the result that there is a reductionin the rate of reaction forming the polymeric materials (as representedby Equation 1) until the mixture is subjected to heat (as illustrated byEquation 3).

In the preparation of the mono-adducts in general, the polyisocyar'iateand the adduct-forming compound are usually dissolved in a suitableinert solvent such as toluene, methyl ethyl ketone, oro-dichlorobenzene. The solutions are stirred together and permitted tostand. The reaction should be caused to take place at a temperaturebelow the decomposition temperature of the desired product andpreferably at a temperature not exceeding approximately C. In mostinstances the reaction will proceed satisfactorily at room temperature.The adduct formed separates from the solution and is removed therefromby filtering or evaporation of the solvent. The time required for theadduct to form will vary from a few minutes to several hours dependingupon the particular reactants used. If a mono-adduct of a polyisocyanateis desired, usually an excess of the polyisocyanate is provided so thatthe product which separates will be substantially pure mono-adduct. Theprecipitated product will probably contain small amounts of unreactedmaterial which, if necessary, can be removed by recrystallization orextraction procedures known to those skilled in the art.

The preparation of the adducts is illustrated by the following exampleswhich are to be interpreted as representative rather than restrictive ofthe scope of this invention.

EXAMPLE 1 4,4-diphenyl diisocyanate (0.15 mol) and tertiary amyl alcohol(0.10 mol) were dissolved in 400 cubic centimeters of dry toluene. Thesolution was refluxed for 5 hours. The mono-adduct began to separatefrom solution during the first hour. The solution was cooled, and themonoadduct removed by filtration. After resuspension and digestionin'petroleum ether and filtration of the solution, the mono-adduct wasair dried at room temperature. A yield of 29% was obtained.

EXAMPLE 2 4,4'-diphenyl diisocyanate (47.2 grams or 0.20 mol) andepsilon caprolactam (11.3 grams or 0.10 mol) were dissolved in 400 cubiccentimeters of toluene. Separation of the mono-adduct started within oneminute after the materials were dissolved. The white, solid product wasseparated from the .solution by filtering and found to contain 22.3 gramof the mono-adduct.

EXAMPLE 3 4,4'-diphenyl diisocyanate (35.4 grams or 0.15 mol) andaceto-acetic ester (13.01 grams or 0.10 mol) were dissolved in 390 gramsof toluene, to which 1 gram of freshly prepared sodium methylate wasadded. After '16 hours at reflux temperatures, the mono-adduct which hadformed and separated from solution was filtered off.

EXAMPLE 4 4,4' -diphenyl diisocyanate (35.4 grams or 0.15 mol) anddiethyl malonate (16.02 grams or 0.10 mol) were teen hours at refluxtemperature, the m'ono-adduct WhlClI had formed and separated fromsolution, was filtered off.

EXAMPLE 4,4'-diphenyl diisocyanate (35.4 grams or 0.15 mol) wasdissolved in 390 grams of toluene by heating. The solution was filteredto remove any undissolved solids. To this solution was added 0.10 mol ofphenyl beta naphthyl amine with stirring. The mono-adduct separated fromsolution. The product was removed from solution by filtering,leaving'the unreacted material in solution. The yield of this first-cropseparation was 8.7 grams of the mono-adduct.

EXAMPLE 6 4,4-diphenyl diisocyanate (35.4 grams or 0.15 mol) wasdissolved in 390 grams of toluene by heating. The solution was filteredto remove any undissolved solids. To this solution was added 0.10 mol ofdiphenyl amine with stirring. The mono-adduct separated from solutionand was removed by filtering, leaving the unreacted material insolution. The yield of this first-crop separation-was 8.7- grams of themono-adduct.

EXAMPLE 7 4,4-diphenyl diisocyanate (0.15 mol) and phthalimide (0.10mol) were dissolved in 440 cubic centimeters of methyl ethyl ketone. Awhite solid separated from solution. The solution was filtered, and ayield of 29.2 grams of monoadduct was obtained.

EXAMPLE 8 4,4'-diphenyl diisocyanate (35.4 grams or 0.15 mol) andsuccinimide (9.91 grams or 0.10 mol) were dissolved in 440 cubiccentimetersof methyl ethyl ketone. A White solid separated from solutionwhich was filtered. A yield of 24.7 grams of the mono-adduct wasobtained.

EXAMPLE 9 EXAMPLE l0 ..'.4,4"diphenyl diisocyanate (23.6 grams or 0.10mol) and mono alpha phenyl ethyl phenol (19.83 grams or 0 .l0,mol).'were dissolved in 390 grams of toluene. After standing for severalhours, the solution was evaporated to rernove the toluene. An oilyliquid remained which solidified on standing. The formed mono-adductshowed a melting point of 8l-86 C.

The procedure set forth in the foregoing examples for the preparationof-mono-adducts of diisocyanates may alsobe employed in the productionof polyadducts of polyisocyanates. Any ofthe adduct-forming materialsset forth above may be reacted with any of the mentioned polyisocyanatesin accordance with the procedures described in the foregoing examples toobtain adducts of the desired type.

I, The theory behind the use of the adducts of polyisocyanates in orderto control the polyfunctional reactivity of'the plurality of -NCO groupspresent may be illustrated, for instance, by the mono-adduct of atriisocy-. anate. In .such a compound, while two NCO groups remainavailable for reaction, the overall trifunctional reactivity of thethree -NCO groups in the original tri-. isocyanate has been reducedtheoretically by one third.

Cit

6 l Such reduction in activity is" desirable as a means of con: trollingthe reactivity of polyisocyanates. It is likewise "to be noted thatthere is'no particular advantage iir'employing, in such a reaction, apolyisocyanate all of Whose NCO-groups have-been.blocked, since reactionof av polymeric nature is prevented even though one free NCO group ispresent in the reacting mixture. This invention therefore applies tothose adducts of polyisocyanates in which at least one -NCO group isinactivated or blocked (subject to being reactivated or unblocked? byapplying heat) and in which there is at least one active NCO group.

The adducts of polyisocyanates are particularly useful as curing orcross-linking agents for the diisocyanatemodified polyesters andpolyesteramides; the polyesteramide urea urethanes,polyester-amidesurethane-urethanes, polyester-amide-amide-urethanes andother similar materials. As described in our co-pendingapplicationsreferred to above, these materials are synthetic poly meric elastomerspossessing outstanding physical properties and will be referred tohereinafter and in the'appended claim as elastomeric'diisocyanate-modified poly esters.

While each'of these materials will be discussed'at le'rigth below, thegeneral chemical reactions, involved in their preparation, may berepresentedby the following illustrations in which R, R, and R" denotedivalent organic radicals.

Preparation of polyester O II I H(0 R )CRiJ)nOH (Z'n-DlIrO in which n isa positive whole number denoting the de gree of polymerization of thepolyester formed.

Preparation of polyesteramide (5) "0 II 1L(HO-RNHg) 7t(H0-'iil-R'COH) in i I H(0R"NCRO) ,.-OH (2n1)HzO Preparation of diisocyanate-modifiedpolyester (6) HO-po1yester-OOOH OCN.R--NOO O H 0 g l I II it(HO-polyester N- C0polyester )...--OH mCOa in Which m is a positivewhole number denoting the number of segments in thediisocyaante-modified, chain-extended polymer. Preparation ofdiisocyanate-modified polyesteramide (7) HO--polyesterernlde-COOHOCN-RNCO -r if O (HO-polyesteramide-'JNR"NJiO-polyesteramlde-il)mOH+mCOs in which m is a positive wholenumber denoting the number of segments in the diisocyanate-modifiied,chain-extended polymer.

Preparation of difsocyanate-modified interpolymers iHO-polyester-0OOH-HzN-IW-NH: OCN-R'NCO in which R" and R representdivalent organic radicals and m represents a positive whole numberdenoting the number of segments in the modified chain-extendedinterpolymer.

Equations 6, 7, 8, 9 and 10 represent the reactions which may'take placein forming the uncured elastomeric polymers according to the limitationsas to acid number, hydroxyl number, amino groups, bifunctionaladditives, and amount of particular diisocyanate used in theirpreparatfion, described in our co-pending applications Serial Numbers187,696, filed September 29, 1950, now U. S. Patent 2,625,532; 305,914,filed August 22, 1952, now U. .5. Patent 2,680,308; 307,900, filedSeptember 4, 1952, now U. S, Patent 2,702,107; and 312,161, filedSeptember 29, 1952, now U. S. Patent 2,625,535.

The mono-adducts of diisocyanates may be conveniently used in thepreparation of these uncured polymers, but it is in the addition of thecuring or cross-linking polyisocyanate that the use of the adductsperforms a particularly valuable function.

The curing or cross-linking of the uncured polymers takes place as theresult of reaction between the NCO groups in the polyisocyanate and thereactive hydrogens in certain groups present in the chain of theextended polymer and certain terminal groups at the ends of the chainextended units. The terminal groups include, of course, hydroxyl,carboxyl, and amino radicals. The groups along the chain include thegroups formed by reaction between an NCO group and a carboxyl, hydroxyl,or amino group, and may be represented as a substituted amide linkage OH ell-lei a carbamic radical (o i-1 I- and a ureylene radical H o H -1 Ir 'rrespectively. Each of these groupings has at least one activehydrogen available for reaction with the -NCO group of thepolyisocyanate.

It is necessary in the fabricating of articles from a rubber orrubber-like material to be able to process the material after theparticular chemical which will ultimately cause its transformation fromthe uncured to the cured state has been added to the uncured elastomericdiisocyanate-modified polyester. The time required to effect suchprocessing is often a matter of several days or even weeks. it isobvious that if the material cures before the processing is complete,subsequent processing or forming is impossible. The use of the adductsof polyisocyanates as curing agents for the elastomeric polymersdescribed will minimize the cross-linking or curing of the polymersduring the fabricating of the material. When the material has beenfabricated into its desired form, curing is effected by the applicationof heat and pressure in accordance with normal practice. The heat causesthe breakdown of the adduct with resultant freeing of the blocked orinactivated -NCO groups, which groups will then react with the reactivehydrogen atoms available in the various linkages along thechain-extended polymer to effect a cross-linking or cure of thematerial.

The particular diisocyanate-modified elastomeric polymers which can becured by reaction with the adducts of polyisocyanates described hereinhave been set forth at length in our co-pending applications referred toabove. They may be grouped in four general classes.

First, the reaction product of (1) a polyester or polyestcramideprepared from at least one dibasic carboxylic acid and at least oneglycol, and/ or at least one amino alcohol, and/ or at least onediamine; the number of hydro gen-bearing amino groups being present inan amount not to exceed 7.5% of the total hydroxyl and hydrogenbearingamino groups present, the polyester or polyesteramide having a hydroxylnumber from 40 to (the preferred range is from 5-0 to 60) and an acidnumber from 0 to 7; and (2) at least one diisocyanate selected from thegroup consisting of 4,4'-diphenyl diisocyanate, 4,4-diphenylene methanediisocyanate, dianisidine diisocyanate, 4,4'-tolidine diisocyanate,1,5-naphthalene diisocyanate, 4,4'-cliphenyl ether diisocyanate, andp-phenylene diisocyaante, the diisocyanate being used in an amountranging from 0.70 to 0.99 (the preferred range is from 0.90 to 0.99) molper mol of polyester or polyesteramide.

Second, the reaction product of (1) a polyester or polyesteramideprepared from at least one dibasic carboxylic acid, and at least oneglycol and/or at least one amino alcohol and/ or at least one diamine,the number of hydrogen-bearing amino groups present being in an amountnot to exceed 30% of the total hydroxyl and hydrogen-bearing aminogroups present, the polyester or polyesteramide having a hydroxyl numberfrom 30 to (the preferred range is from 50 to 60) and an acid numberfrom 9 to 12; and (2) at least one tolylene diisocyanate, thediisocyanate being used in an amount ranging from 0.85 to 1.10 (thepreferred range is from 0.90 to 1.00) mols per mol of polyester orpolyesteramide.

Third, the reaction product resulting from the reaction of a mixturecomprising (1) a polyester prepared from bifunctional ingredientsincluding at least one dibasic carboxylic acid containing at least threecarbon atoms, and at least one glycol, said polyester having a hydroxylnumber from 30 to 140 (the preferred range is from 50 to 60) and an acidnumber from 0 to 12; (2) at least one bifunctional additive selectedfrom the group consisting of diarnines, amino alcohols, dicarboxylicacids, hydroxy carboxylic acids, amino carboxylic acids and the ureas,guanidines, and thioureas containing a primary amino group, saidbifunctional additive being used in an amount such that the total numberof -NH2 and COOH equivalents present in said bifunctional reactant shallbe from 0.06 to 0.24 equivalents per mol of polyester, and (3) at leastone tolylene diisocyanate, the diisocyanate being used in an amountequal to the sum of from 0.85 mol to 1.10 (the preferred range is from0.90 to 1.00) mols of diisocyanate per mol of polyester and the molaramount of diisocyanate equivalent to the mols of said bifunctionaladditive used.

Fourth, the reaction product resulting from the reaction of a mixturecomprising (1) a polyester prepared from bifunctional ingredientsincluding at least one dibasic carboxylic acid containing at least threecarbon atoms and at least one glycol, said polyester having a hydroxylnumber between 40 and 100 (the preferred range is from 50 to 60) and anacid number from 0 to 7; (2) at least one bifunctional additive selectedfrom the group consisting of diarnines, amino alcohols, dicarboxylicacids, hydroxy carboxylic acids, amino carboxylic acids and. the ureas,guanidines, and thioureas containing a primary amino group, saidbifunctional additive beingused in an amount such that the total numberof NH2 actant shall be from 0.06 to 0.48 equivalents per mol ofpolyester, and (3) at least one diisocyanate selected from the groupconsisting of 4,4'-diphe'nyl"diisocyanate, 4,4,- diphenylene methanediisocyanate, 4,'4'-tolidine diisocyanate, dianisidine diisocyanate,1,5-naphthalene diisocyanate, 4,4'-diphenyl ether diisocyanate, andp-phenylene diisocyanate, the diisocyanate beingused in an amount equalto the sum of from 0.70 mol to 0.99 (the preferred range is from 0.90 to0.99) mol of diisocyanate per mol of polyester and the molar amount ofdiisocyanate equivalent to the mols of bifunctional additive used.

Listed below are the reactants used to form some preferred polyestersand polyesteramides which, when prepared and subsequently modified by adiisocyanate or other additive in accordance with the appropriatelimitations indicated in the description of the four types of syntheticelastomers, will produce elastomeric products.

I. Ethylene glycols plus adipic acid.

2 Propylene glycol 1,2 plus adipic acid.

. Ethylene glycol (80 mol percent),

1,2 (20 mol percent) plus adipic acid.

. Ethylene glycol (80 mol percent),

1,2 (20 mol percent) plus azelaic acid.

5. Ethylene glycol (80 mol percent),

1,2 (20 mol percent) plus sebacic acid.

6. Ethylene glycol (80 mol percent), propylene glycol 1,2 (20 molpercent) plus dilinoleic acid (20 mol percent) adipic acid (80 molpercent).

7. Ethylene glycol (80 mol percent), glycerine monoethyl ether (20 molpercent) plus adipic acid.

8. Ethylene glycol (80 mol percent), butylene glycol 1,4

(20 mol percent) plus adipic acid.

propylene glycol propylene glycol propylene glycol 9. Ethylene glycol(80 mol percent), propylene glycol 1,3 (20 mol percent) plus adipicacid.

10. Ethylene glycol (80 mol percent), pentane diol 1,5

1,2 (20 mol percent) plus maleic acid (from 3 to-6.

mol percent), adipic acid (from 9 7 to 94 mol percent).

14. Ethylene glycol (80 mol percent), propylene glycol 1,2 (from 19 to17 mol percent), piperazine (from 1 to 3 mol percent) plus adipic acid.

15. Ethylene glycol (80 mol percent), propylene glycol 1,2 (from 18 tomol percent), dihydroxye'thyl'analine (from 2 to 15 mol percent) plusadipic acid.

l6. Ethylene glycol (80 mol percent), diethylene glycol (20 mol percent)plus adipic acid. 1

17. Ethylene glycol (from 90 to mol percent), pro pylene glycol 1,2(fromlO to 90 mol'percent) plus adipic acid.

18. Ethylene glycol (from 90 to 10 mol percent), propylene glycol 1,2(from 10 to 90 mol percent) plus azelaic acid.

The diisocyanates which are preferred when used to form the unvulcanizedmodified polyesters and polyesteramides, are 4,4-diphenyl diisocyanate,1,5-naphthalene diisocyanate, the meta tolylene diisocyanates, such as2,4- and 2,6-tolylene diisocyanate, and 4,4'-diphenylene methanediisocyanate. If meta tolylene diisocyanate is to be used, a convenientmethod of adding it is in the form of one of its dimers such as thedimer of 2,4 tolylene diisocyanate of the following formula:

The dimer is less toxic than the monomeric material. 1

Of the first class of elastomeric polymers described above, those ofparticular interest are the rubber-like polymers resulting frompolyethylene adipate modified by 4,4- diphenyl diisocyanate,1,5-naphthalene diisocyanate, 4,4- diphenylene methane diisocyanate, ormixtures thereof; polypropylene 1,2 adipate modified by 4,4-diphenyldiisocyanate, 1,5-naphthalene diisocyanate, 4,4-diphenylene methanediisocyanate, or mixtures thereof; polyethylene mol percent) propylene1,2 (20 mol percent) adipate modified by 4,4-diphenyl diisocyanate,1,5-naphthalene diisocyanate, 4,4-diphenyl methane diisocyanate, ormixtures thereof; polyethylene (80 mol percent) propylene 1,2 (20 molpercent) azelate'modified by 4,4'-diphenyl diisocyanate, 1,5-naphthalenediisocyanate, -4,4-diphenylene methane diisocyanate, or mixturesthereof; and polyethylene (80 mol percent)-propylene 1,2 (from 19 to 17mol percent) piperazine (from 1 to 3 mol percent) adipate modified by4,4'-diphenyl diisocyanate, 1,5- naphthalene diisocyanate,4,4'-diphenylene methane diisocyanate, or mixtures thereof. Thesepolymers, when cured, have been found to possess outstanding physicalproperties. I

Of the second class of elastomeric polymers described above, those ofparticularinterest are the rubber-like polymers resulting frompolyethylene adipate modified by a meta tolylene diisocyanate,polypropylene 1,2 adipate modified by a meta tolylene diisocyanate,polyethylene 80 mol percent) propylene 1,2 (20 mol percent) adipatemodified by a meta tolylene diisocyanate, polyethylene (80 mol percent)propylene 1,2 (20 mol percent) azelate modified by a meta tolylenediisocyanate, and polyethylene '(80 mol percent) propylene 1,2 (from 19to 17 mol percent) piperazine (from 1 to 3 mol percent) adipate modifiedby a meta tolylene diisocyanate.

Mixtures of meta tolylene diisocyanates such as mixtures of 2,4- and2,6-tolylene diisocyanates may also be used.

Of the third class of elastomeric interpolymers described above, thoseof particular interest are the rubberlike materials resulting from i (1)Polyethylene adipate modified by a meta tolylene diisocyanate, and byethylene diamine, tetramethylene diamine, hexamethylenediamine, ethanolamine, benzidine, 4,4-diamino diphenyl methane or mixtures thereof.

' (2) Polypropylene 1,2-adipate modified by a meta tolylenediisocyanate, and by ethylene diamine, tetramethylene diamine,hexamethylene diamine, ethanol" amine, benzidine, 4,4'-diamino diphenylmethane or mixtures thereof.

(3) Polyethylene (80 mol percent) propylene 1,2 (20 mol percent) adipatemodified by a meta tolylene diisocyanate, and by ethylene diamine,tetramethylene diamine, hexamethylene diamine, ethanol amine, benzidine,4,4-diamino diphenyl methane or mixtures thereof.

(4) Polyethylene (80 mol percent)'propylene 1,2 20 mol percent) azelatemodified by a meta tolylene, di=' diamine, ethanol amine, benzidine,4,4-diamino diphenyl methane or mixtures thereof.

(2) Polypropylene 1,2 adipate modified by 4,4'-diphenyl diisocyanate,1,5-naphthalene diisocyanate, 4,4-diphenylene methane diisocyanate, ormixtures thereof, and by ethylene diamine, tetramethylene diamine,hexa-- 11 methylene diamine, ethanol amine, benzidine, 4,4'-diaminodiphenyl methane or mixtures thereof.

(3) Polyethylene (80 mol percent) propylene 1,2 (20 mol percent) adipatemodified by 4,4-diphenyl diisocyanate, 1,5-naphthalene diisocyanate,4,4'-diphenylene methane diisocyanate, or mixtures thereof, and byethylene diamine, tetramethylene diamine, hexamethylene diamine, ethanolamine, benzidine, 4,4'-diamino diphenyl methane or mixtures thereof.

(4) Polyethylene (.80 mol percent) propylene 1,2 (20 mol percent)azelate modified by 4,4-diphenyl diisocyanate, 1,5-naphthalenediisocyanate, 4,4-diphenylene methane diisocyanate, or mixtures thereof,and by ethylene diamine, tetramethylene diamine, hexamethylene diamine,ethanol amine, benzicline, 4,4-diamino diphenyl methane or mixturesthereof.

The amount of polyisocyanate adduct required to cure or cross link thechain-extended polymers and interpol-ymers described above must be heldwithin certain limits. Any adduct of an organic diisocyanate,polyisocyanate or mixtures of adducts of diisocyanates,polyisoc-yanates, ,or both, may be added in this step. When curing thepolymers of the first and second classes, enough adduct must be added tothe polymer so that the total amount of -NCO equivalents (whether activeor inactive and including that added in the formation of the polymer)shall be from 2.80 to 3.20 equivalents per mol of polyester orpolyesteramide. In addition to this, an amount of adduct equivalent totwice the molar amount of bi functional additive used in preparing theinterpolymer must be employed in the curing of the interpolymers of thethird and fourth classes. Smaller amounts of polyisocyanate adductsadded to cure the polymer or interpolymer will result in an under-curedproduct. The use of greater amounts is a waste of material with noimproved properties in the cured product and in some cases produces acured material having properties more resinous than rubber-like. If atriisocyanate adduct or tetraisocyan-ate adduct is used in place of adiisocyanate adduct to eifect a cure, not as much material, on a molbasis, need be used, since the curing or cross-linking of the linearmolecules depends upon the number of -NCO groups present in the curingagent. For example, if 0.50 mol of a diisocyanate adduct gives asatisfactory cure of a diisocyanate-modified polyester orpolyesteramide, the use of approximately 0.25 mol of a tetraisocyanateadduct will result in a similar state of cure.

The actual curing of the polymer or interpolymer is accomplished bymethods familiar to those skilled in the art. best cure for anyparticular polymer or interpolymer will of course vary as is the casewith the curing of conventional natural rubber compounds. The cure forbest results should be accomplished by the use of dry heat sinceexposure of the polymer to hot water or steam results in a partialdegeneration of the cured material.

The following examples, in which parts are by weight, illustratepreparation of a polyester, a diisocyanate-modified polyester, and thecuring of the modified polyesters using the polyisocyanate adductsaccording to the teachings of this invention.

EXAMPLE 11 Preparation of a typical polyester Adipic acid (3515 parts)was placed in a liter, 3- necked flask fitted with a stirrer,thermo-couple well, gas inlet tube, distilling head, and condenser. Tothe acid were added 1064 parts of ethylene glycol and 869 parts ofpropylene 1,2 glycol. The molar ratio of dibasic acid to glycol is 11.19. The mixture was heated to 130l60 C. until most of the water haddistilled off. The temperature was then gradually raised to 200 C., thepressure being gradually reduced to mm. and nitrogen being'bubbledthrough the melt. After 23 /2 hours a The time and temperature requiredto effect the 12 soft white waxy solid was obtained. Determinationsshowed the acid number to be 3.5 and the hydroxyl number to be 58.6.

EXAMPLE 12 Preparation of the diisocyanate-modified polymer A quantityof polyester was prepared from adipic acid, ethylene glycol, andpropylene 1,2 glycol according to the general method and insubstantially the same ratios a shown in Example 11. This polyester hadan acid number of 3.1 and a hydroxyl number of 55.6. After heating 2270parts of this polyester in a steamheated Baker Perkins mixer to C.,4,4-diphenyldiisocyanate (280.3 parts of 95.7% purity or 0.96 mol permol of polyester) was added. After ten minutes of mixing, the hot meltwas poured into a carnauba wax coated tray and baked for 8 hours at C.The resulting' polymer had excellent processing characteristics on arubber mill. Tests showed the following physical propertiesintrinsicviscosity 1.69, percent gel 3.9, and softening point186 C.

EXAMPLE 13 A rubber-like polymer (100 parts) prepared according to theprocedure outlined by Example 12, was mixed with 8.19 parts of themono-adduct of epsilon-caprolactam and 4,4'-diphenyl diisocyanate on arubber mill. (See Example 2.) The test sheets prepared from the polymerwere heated for twenty-six hours at 248 F. in an oven. The sheets werethen press-cured for 35 minutes at 300 F. Test results showed the curedmaterial to have a tensile strength of 4050 pounds per square inch, anelongation of 925% and a hardness (Shore Type A) of 55.

EXAMPLE 14 A rubber-like polymer (100 parts) prepared according to theprocedure outlined by Example 12 was mixed with 9.45 parts of themono-adduct prepared from 4,4-diphenyl diisocyanate andZ-mercaptobenzothiazole. (See Example 9.) Test sheets were press-curedfor 70 minutes at 300 F. Test results showed the cured material to havea tensile strength of 2400 pounds per square inch, an elongation. of860% and a hardness (Shore Type A) Of 56'.

EXAMPLE 15 A rubber-like polymer (100 parts) prepared according to theprocedure outlined by Example 12 was mixed with 8.48 parts of themono-adduct prepared from 4,4'-diphenyl diisocyanate and succinimide.(See Example 8.) Test sheets were press-cured for 70 minutes at 300 F.Test results showed the cured material to have a tensile strength of2700 pounds per square inch, an elongation of 925% and. a hardness(Shore Type A) of 55.

EXAMPLE 16 A rubber-like polymer (100 parts) prepared according to theprocedure outlined by Example 12, except that 1,5- naphthalenediisocyanate was used as a molar replacement for 4,4'-diphenyldiisocyanate, was mixed with 12.2 parts of. the mono-adduct preparedfrom 1,5-naphthalene diisocyanate and diethyl malonate. The mix washeated for two hours at 300 F. and then press-cured for one hour at, 300F. Test results showed the cured material to have a tensile strength of2660 pounds per square inch, 211 elongation of 820% and a hardness(Shore Type A) of To illustrate the advantage gained by the use of theadducts of polyisoc'y'anates as cross-linking or curing agents for themodified polyesters and polyesteramides, the following table presentsthe results obtained by running plastic flow tests on the compoundedmaterial at given intervals after the curing agent had been added to theelastomeric polymer. The figures shown in the table represent OriginalAfter After 2 days days 7 Control 333 667 3,000 Example 13 114 158 121Example 1 179 223 Example 15. 191 171 It is evident from these teststhat the control sample, using 4,4-diphenyl diisocyanate, has beensubstantially cured or cross-linked after 5 days aging at roomtemperature while the other samples, containing the monoadducts of4,4'-diphenyl diisocyanate, remain processible. The samples preparedusing the adducts can, after 5 days aging, still be worked or processedthrough the various fabricating operations necessary to produce afinished product, while the control, after the same period of time, hascured to a point where it is no longer processible nor useable infabricating a finished product.

The elastomeric polymers and interpolymers prepared according to thepractices of this invention are, in general, useful in thoseapplications where natural rubber or rubber-like materials are used. Inparticular they may be used in tires, belts, hose, sheet packing,gaskets, molded goods, floor mats, dipped goods, sheeting, tank lining,soles, heels, covered rolls, and other mechanical and industrial goods.

This application is a continuation-in-part of our copending applicationSerial No. 193,518, filed November 1, 1950, now abandoned.

While certain representative embodiments and details have been shown forthe purpose of illustrating the invention, it will be apparent to thoseskilled in this art that various changes and modifications may be madetherein without departing from the spirit or scope of the invention.

We claim:

1. A process which comprises forming a mixture of (1) the reactionproduct of a polyisocyanate and another compound selected from the groupconsisting of tertiary alcohols, secondary aromatic amines, mercaptans,lactams, monohydric phenols, imides, and compounds containing enolizablehydrogen, said reaction product containing at least one active -NCOgroup and at least one inactivated -NCO group, and (2) an elastomericdiisocyanatemodified linear polymer and heating said mixture to releasethe inactivated -NCO groups present in said reaction product and toeffect a cure of said elastomeric diisocyanate-modified linear polymer,said elastomeric diisocyanate-modified linear polymer being selectedfrom the group consisting of: (A) the product resulting from thereaction of a mixture comprising (3) a material prepared frombifunctional ingredients including at least one dibasic carboxylic acidand at least one complementary bifunctional reactant in which thefunctional groups are selected from the class consisting of the hydroxylgroup and the hydrogen-bearing amino groups, the hydrogenbearing aminogroups being present in an amount not to exceed 7.5% of the totalfunctional groups of said complementary bifunctional reactant, saidmaterial having a hydroxyl number from 40 to 100 and an acid number from0 to 7, and (4) at least one diisocyanate selected from the groupconsisting of 4,4'-diphenyl diisocyanatc; 4,4'-diphenylene methanediisocyanate; dianisidine diisocyanate; 4,4'-tolidine diisocyanate;1,5-naphthalene diisocyanate; 4,4-diphenyl ether diisocyanate, andp-phenylene diisocyanate, the diisocyanate being used in an amountranging from 0.70 to 0.99 mol per mol of said material; (B) the productresulting from the reaction of a mixture comprising (5) a materialprepared from bifunctional in gredients including at least one dibasiccarboxylic acid and at least one complementary bifunctional reactant inwhich the functional groups are selected from the class consisting ofthe hydroxyl group and the hydrogen-bearing amino groups, thehydrogen-bearing groups being present in an amount not to exceed 30% ofthe total functional groups of said complementary bifunctional reactant,said material having a hydroxyl number from 30 to 140 and an acid numberfrom 0 to 12, and (6) at least one tolylene diisocyanate used in anamount ranging from 0.85 to 1.10 mols per mol of said material; (C) theproduct resulting from the reaction of a mixture comprising (7) apolyester prepared from bifunctional ingredients including at least onedibasic carboxylic acid containing at least three carbon atoms, and atleast one glycol, said polyester having an hydroxyl number from 30 to140 and an acid number from 0 to 12; (8) at least one bifunctionaladditive selected from the group consisting of diamines, amino alcohols,dicarboxylic acids, amino carboxylic acids, hydroxy carboxylic acids andthe ureas, guanidines, and thioureas containing a primary amino group,said biiunctional additive being used in an amount such that the totalnumber of NH2 and COOH equivalents present in said bifunctional reactantshall be from 0.06 to 0.24 equivalents per mol of polyester, and (9) atleast one tolylene diisocya-.

nate used in an amount equal to the sum of from 0.85 mols to 1.10 molsofdiisocyanate per mol of polyester plus the molar amount ofdiisocyanate equivalent to the mols of said bifunctional additive used;(D) the product resulting from the reaction of a mixture comprising (10)a polyester prepared from bifunctional ingredients including at leastone dibasic carboxylic acid containing at least three carbon atoms andat least one glycol, said polyester having a hydroxyl number between 40and and an acid number from 0 to 7, (11) at least one bifunctionaladditive selected from the group consisting of diamines, amino alcohol,dicarboxylic acids, amino carboxylic acids, hydroxy carboxylic acids andthe ureas, guanidines and thioureas containing a primary amino group,said bifunctional additive being used in an amount such. that the totalnumber of -NH2 and COOH equivalents present in said bifunctionalreactant shall be from 0.06 to 0.48 equivalents per mol of polyester,and (12) at least one diisocyanate selected from the group consisting of4,4'-diphenyl diisocyanate; 4,4'-diphenylene methane diisocyanate; 4,4-tolidine diisocyanate; dianisidine diisocyanate; 1,5-naphthalenediisocyanate; 4,4'-diphenyl ether diisocyanate, and p-phenylenediisocyanate, the diisocyanate being used in an amount equal to the sumof from 0.70 mol to 0.99 mol of diisocyanate per mol of polyester plusthe molar amount of diisocyanate equivalent to the mols of bitunctionaladditive used, (A) and (B) being mixed with a sufficient amount of saidreaction product to bring the total number of NCO equivalents andinactivated NCO equivalents present to from 2.80 to 3.20 equivalents permol of said material and (C) and (D) being mixed with a suflicientamount of said reaction product to bring the total number of NC()equivalents and inactivated -NCO equivalents present to the sum of from2.80 to 3.20 equivalents per mol of said polyester plus twice the molaramount of bifunctional additive used in the preparation of saidelastomeric diisocyanate-modified linear polymer.

2. The process defined by claim 1 in which the elastomericdiisocyanate-modified linear polymer results from the reaction of amixture comprising (A) a polyester prepared from at least one dibasiccarboxylic acid and at least one glycol, said polyester having ahydroxyl number from 40 to 100 and an acid number from 0 to 7 and (B)4,4-diphenyl diisocyanate used in an amount ranging from 0.90 to 0.99mol per mol of said polyester.

3. The process defined by claim 1 in which the elastomericdiisocyanate-modified linear polymer results from 15 the reaction of amixture comprising (A) a polyester prepared from at least one dibasiccarboxylic acid and at least one glycol, said polyester having ahydroxyl number from 30 to 140 and an acid. number from to 12 and (B)tolylene diisocyanate used in an amount ranging from 0.90 to 1.00 molper mol. of said polyester.

4. The process defined by claim 1 in which the elastomericdiisocyanate-modified linear polymer results from the reaction of amixture comprising (A) a polyester prepared from at least one dibasiccarboxylic acid containing at least three carbon atoms and at least oneglycol, said polyester having a hydroxyl number from 30 to 140 and anacid number from 0 to 12, (B) a diamine used in an amount such that thetotal number of NH2 equivalents is from 0.06 to 0.24 equivalents per molof polyester and (C) tolylene diisocyanate used in an amount equal tothe sum. of from 0.90 to 1.00 mol per mol of polyester plus the molaramount of diisocyanate equivalent to the mols of diamine used.

5. The process defined by claim 1 in which the elastomericdiisocyanate-modified linear polymer results from the reaction of amixture comprising (A) a polyester prepared irom at least one dibasiccarboxylic acid containing at least three carbon atoms and at least oneglycol, said polyester having a hydroxyl number from 40 to 100 and anacid number from 0 to 7, (B) a diamine used in an amount such that thetotal number of NH2 equivalents is from 0.06 to 0.48 equivalents per molof polyester and (C) 4,4-diphenyl diisocyanate used in an amount equalto the sum of. from 0.90 to 0.99 mol per mol of polyester plus the molaramount of diisocyanate equivalent to the mols of diamine used.

6. The process defined by claim 1 in which the clastomericdiisocyanate-modified linear polymer results from the reaction of amixture comprising (A) a polyester prepared from at least one dibasiccarboxylic acid containing at least one glycol, said polyester having ahydroxyl number from to and an acid number from 0 to 7, (B) a diamineused in an amount such that the total number of NI-Iz equivalents shallbe from 0.06 to 0.48 equivalents per mol of polyester and (C)4,4'-tolidine diisocyanate used in an amount equal to the sum of from0.90 to 0.99 mol per mol of polyester plus the molar amount ofdiisocyanate equivalent to the mols of diamine used.

References Cited in the file of this patent UNITED STATES PATENTS2,625,532 Seeger Jan. 13, 1953 2,625,535 Mastin et al Jan. 13, 19532,683,727 Mastin et al. July 13, 1954 2,683,728 Mastin et al. July 13,1954 2,683,729 Seeger et al. July 13, 1954 2,698,845 Mastin et al. Jan.4, 1955 OTHER REFERENCES Pinner: Plastics (London), May 1947, pages257-262. Bayer: Modern Plastics, June 1947, pages 149, 151, 152, 250,252, 254, 256, 258, 260.

